title: The role of reflectance confocal microscopy as an aid in the diagnosis of collision tumors.
abstract: BACKGROUND
  The term 'collision tumor' refers to the association of 2 or more different neoplasms within the same lesion. The association of a benign neoplasm with a malignant neoplasm is of particular significance and warrants diagnostic accuracy.
  
  
  OBJECTIVE
  The purpose of our study was to see if reflectance confocal microscopy (RCM) was a valuable tool when dealing with collision tumors.
  
  
  METHODS
  We retrospectively evaluated 24 histologically confirmed cases of collision tumors, which were initially assessed using dermoscopy and RCM.
  
  
  RESULTS
  The malignancy most commonly detected in association with collision tumors was basal cell carcinoma (BCC) (n = 13), followed by melanoma (n = 5, of which 2 collided with BCC) and squamous cell carcinoma in situ (n = 4). Seborrheic keratoses were the most common benign neoplasms found in association with collision tumors (n = 18), followed by nevi (n = 7). Dermoscopy revealed the malignant component in 14 out of 20 lesions compared to RCM, which revealed a malignant component in 19 out of 20 neoplasms. There was excellent concordance between RCM and histopathology with regard to the identification of a malignant component within a tumor (kappa value >0.9).
  
  
  CONCLUSIONS
  The dermatoscope and the reflectance confocal microscope, when used in conjunction, are valuable tools aiding in the diagnosis of collision tumors.
authors.affiliation: Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Elvira
authors.initials: E
authors.lastname: Moscarella
authors.forename: Harold
authors.initials: H
authors.lastname: Rabinovitz
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Oliviero
authors.forename: Lise
authors.initials: L
authors.lastname: Brown
authors.forename: Caterina
authors.initials: C
authors.lastname: Longo
authors.forename: Iris
authors.initials: I
authors.lastname: Zalaudek
authors.forename: Simonetta
authors.initials: S
authors.lastname: Piana
authors.forename: Francesca
authors.initials: F
authors.lastname: Farnetani
authors.forename: Aimilios
authors.initials: A
authors.lastname: Lallas
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Argenziano
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pellacani
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D046169:Dermoscopy / Q000379:methods*; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000473:pathology*